Biodegradable literally can refer to anything. Everything we make comes from the earth so everything we throw away will eventually return to the earth. Tricky word, try to avoid products that only market themselves as biodegradable.
Compostable refers to products that can safely decompose and give vital nutrients back to the earth leaving no toxic residues and zero sign of the original product, creating a perfect zero-waste life cycle.
Recyclable means that a product can be melted or broken down to the original substance and recreated into new products. This often refers to plastic, metal, glass, fabric. These products will still end up in a landfill, eventually.